Nikon issued D750 service advisory for shading from shutter problem, to check whether you camera is affected by the issue, click on the link below and enter you Nikon D750 serial numbers, if you camera is affected by the issue than requesting repair will be displayed.
Click here to check your Nikon D750 Serial No
Even is the warranty has expired and your Nikon D750 camera is affected by the issue, don’t worry, Nikon service center will keep your camera, and examine and repair the camera’s shutter free of charge.
source – Nikon
Also see – Recommended Lenses for Nikon D750 DSLR
